---
title: "Retrievers"
---

A [retriever](/oss/langchain/retrieval#building-blocks) is an interface that returns documents given an unstructured query.
It is more general than a vector store.
A retriever does not need to be able to store documents, only to return (or retrieve) them.
Retrievers can be created from vector stores, but are also broad enough to include [Wikipedia search](/oss/integrations/retrievers/wikipedia/) and [Amazon Kendra](/oss/integrations/retrievers/amazon_kendra_retriever/).

Retrievers accept a string query as input and return a list of [Documents](https://python.langchain.com/api_reference/core/documents/langchain_core.documents.base.Document.html) as output.

Note that all [vector stores](/oss/concepts/vectorstores) can be [cast to retrievers](/oss/how-to/vectorstore_retriever/).
Refer to the vector store [integration docs](/oss/integrations/vectorstores/) for available vector stores.
This page lists custom retrievers, implemented via subclassing [BaseRetriever](/oss/how-to/custom_retriever/).

## Bring-your-own documents

The below retrievers allow you to index and search a custom corpus of documents.

| Retriever | Self-host | Cloud offering | Package |
|-----------|-----------|----------------|---------|
| [AmazonKnowledgeBasesRetriever](/oss/integrations/retrievers/bedrock) | ❌ | ✅ | [langchain-aws](https://python.langchain.com/api_reference/aws/retrievers/langchain_aws.retrievers.bedrock.AmazonKnowledgeBasesRetriever.html) |
| [AzureAISearchRetriever](/oss/integrations/retrievers/azure_ai_search) | ❌ | ✅ | [langchain-community](https://python.langchain.com/api_reference/community/retrievers/langchain_community.retrievers.azure_ai_search.AzureAISearchRetriever.html) |
| [ElasticsearchRetriever](/oss/integrations/retrievers/elasticsearch_retriever) | ✅ | ✅ | [langchain-elasticsearch](https://python.langchain.com/api_reference/elasticsearch/retrievers/langchain_elasticsearch.retrievers.ElasticsearchRetriever.html) |
| [VertexAISearchRetriever](/oss/integrations/retrievers/google_vertex_ai_search) | ❌ | ✅ | [langchain-google-community](https://python.langchain.com/api_reference/google_community/vertex_ai_search/langchain_google_community.vertex_ai_search.VertexAISearchRetriever.html) |


## External index

The below retrievers will search over an external index (e.g., constructed from Internet data or similar).

| Retriever | Source | Package |
|-----------|---------|---------|
| [ArxivRetriever](/oss/integrations/retrievers/arxiv) | Scholarly articles on [arxiv.org](https://arxiv.org/) | [langchain-community](https://python.langchain.com/api_reference/community/retrievers/langchain_community.retrievers.arxiv.ArxivRetriever.html) |
| [TavilySearchAPIRetriever](/oss/integrations/retrievers/tavily) | Internet search | [langchain-community](https://python.langchain.com/api_reference/community/retrievers/langchain_community.retrievers.tavily_search_api.TavilySearchAPIRetriever.html) |
| [WikipediaRetriever](/oss/integrations/retrievers/wikipedia) | [Wikipedia](https://www.wikipedia.org/) articles | [langchain-community](https://python.langchain.com/api_reference/community/retrievers/langchain_community.retrievers.wikipedia.WikipediaRetriever.html) |


## All retrievers

> **Note:** The descriptions in the table below are truncated for readability.

<Columns cols={3}>
<Card title="Activeloop Deep Memory" icon="link" href="/oss/integrations/retrievers/activeloop" arrow="true" cta="View guide" />
<Card title="Amazon Kendra" icon="link" href="/oss/integrations/retrievers/amazon_kendra_retriever" arrow="true" cta="View guide" />
<Card title="Arcee" icon="link" href="/oss/integrations/retrievers/arcee" arrow="true" cta="View guide" />
<Card title="Arxiv" icon="link" href="/oss/integrations/retrievers/arxiv" arrow="true" cta="View guide" />
<Card title="AskNews" icon="link" href="/oss/integrations/retrievers/asknews" arrow="true" cta="View guide" />
<Card title="Azure AI Search" icon="link" href="/oss/integrations/retrievers/azure_ai_search" arrow="true" cta="View guide" />
<Card title="Bedrock (Knowledge Bases)" icon="link" href="/oss/integrations/retrievers/bedrock" arrow="true" cta="View guide" />
<Card title="BM25" icon="link" href="/oss/integrations/retrievers/bm25" arrow="true" cta="View guide" />
<Card title="Box" icon="link" href="/oss/integrations/retrievers/box" arrow="true" cta="View guide" />
<Card title="BREEBS (Open Knowledge)" icon="link" href="/oss/integrations/retrievers/breebs" arrow="true" cta="View guide" />
<Card title="Chaindesk" icon="link" href="/oss/integrations/retrievers/chaindesk" arrow="true" cta="View guide" />
<Card title="ChatGPT plugin" icon="link" href="/oss/integrations/retrievers/chatgpt-plugin" arrow="true" cta="View guide" />
<Card title="Cognee" icon="link" href="/oss/integrations/retrievers/cognee" arrow="true" cta="View guide" />
<Card title="Cohere reranker" icon="link" href="/oss/integrations/retrievers/cohere-reranker" arrow="true" cta="View guide" />
<Card title="Cohere RAG" icon="link" href="/oss/integrations/retrievers/cohere" arrow="true" cta="View guide" />
<Card title="Contextual AI Reranker" icon="link" href="/oss/integrations/retrievers/contextual" arrow="true" cta="View guide" />
<Card title="Dappier" icon="link" href="/oss/integrations/retrievers/dappier" arrow="true" cta="View guide" />
<Card title="DocArray" icon="link" href="/oss/integrations/retrievers/docarray_retriever" arrow="true" cta="View guide" />
<Card title="Dria" icon="link" href="/oss/integrations/retrievers/dria_index" arrow="true" cta="View guide" />
<Card title="ElasticSearch BM25" icon="link" href="/oss/integrations/retrievers/elastic_search_bm25" arrow="true" cta="View guide" />
<Card title="Elasticsearch" icon="link" href="/oss/integrations/retrievers/elasticsearch_retriever" arrow="true" cta="View guide" />
<Card title="Embedchain" icon="link" href="/oss/integrations/retrievers/embedchain" arrow="true" cta="View guide" />
<Card title="FlashRank reranker" icon="link" href="/oss/integrations/retrievers/flashrank-reranker" arrow="true" cta="View guide" />
<Card title="Fleet AI Context" icon="link" href="/oss/integrations/retrievers/fleet_context" arrow="true" cta="View guide" />
<Card title="Galaxia" icon="link" href="/oss/integrations/retrievers/galaxia-retriever" arrow="true" cta="View guide" />
<Card title="Google Drive" icon="link" href="/oss/integrations/retrievers/google_drive" arrow="true" cta="View guide" />
<Card title="Google Vertex AI Search" icon="link" href="/oss/integrations/retrievers/google_vertex_ai_search" arrow="true" cta="View guide" />
<Card title="Graph RAG" icon="link" href="/oss/integrations/retrievers/graph_rag" arrow="true" cta="View guide" />
<Card title="GreenNode" icon="link" href="/oss/integrations/retrievers/greennode_reranker" arrow="true" cta="View guide" />
<Card title="IBM watsonx.ai" icon="link" href="/oss/integrations/retrievers/ibm_watsonx_ranker" arrow="true" cta="View guide" />
<Card title="JaguarDB Vector Database" icon="link" href="/oss/integrations/retrievers/jaguar" arrow="true" cta="View guide" />
<Card title="Kay.ai" icon="link" href="/oss/integrations/retrievers/kay" arrow="true" cta="View guide" />
<Card title="Kinetica Vectorstore" icon="link" href="/oss/integrations/retrievers/kinetica" arrow="true" cta="View guide" />
<Card title="kNN" icon="link" href="/oss/integrations/retrievers/knn" arrow="true" cta="View guide" />
<Card title="LinkupSearchRetriever" icon="link" href="/oss/integrations/retrievers/linkup_search" arrow="true" cta="View guide" />
<Card title="LLMLingua Document Compressor" icon="link" href="/oss/integrations/retrievers/llmlingua" arrow="true" cta="View guide" />
<Card title="LOTR (Merger Retriever)" icon="link" href="/oss/integrations/retrievers/merger_retriever" arrow="true" cta="View guide" />
<Card title="Metal" icon="link" href="/oss/integrations/retrievers/metal" arrow="true" cta="View guide" />
<Card title="NanoPQ (Product Quantization)" icon="link" href="/oss/integrations/retrievers/nanopq" arrow="true" cta="View guide" />
<Card title="Nebius" icon="link" href="/oss/integrations/retrievers/nebius" arrow="true" cta="View guide" />
<Card title="needle" icon="link" href="/oss/integrations/retrievers/needle" arrow="true" cta="View guide" />
<Card title="Nimble" icon="link" href="/oss/integrations/retrievers/nimble" arrow="true" cta="View guide" />
<Card title="Outline" icon="link" href="/oss/integrations/retrievers/outline" arrow="true" cta="View guide" />
<Card title="Permit" icon="link" href="/oss/integrations/retrievers/permit" arrow="true" cta="View guide" />
<Card title="Pinecone Hybrid Search" icon="link" href="/oss/integrations/retrievers/pinecone_hybrid_search" arrow="true" cta="View guide" />
<Card title="Pinecone Rerank" icon="link" href="/oss/integrations/retrievers/pinecone_rerank" arrow="true" cta="View guide" />
<Card title="PubMed" icon="link" href="/oss/integrations/retrievers/pubmed" arrow="true" cta="View guide" />
<Card title="Qdrant Sparse Vector" icon="link" href="/oss/integrations/retrievers/qdrant-sparse" arrow="true" cta="View guide" />
<Card title="RAGatouille" icon="link" href="/oss/integrations/retrievers/ragatouille" arrow="true" cta="View guide" />
<Card title="RePhraseQuery" icon="link" href="/oss/integrations/retrievers/re_phrase" arrow="true" cta="View guide" />
<Card title="Rememberizer" icon="link" href="/oss/integrations/retrievers/rememberizer" arrow="true" cta="View guide" />
<Card title="SEC filing" icon="link" href="/oss/integrations/retrievers/sec_filings" arrow="true" cta="View guide" />
<Card title="Self-querying retrievers" icon="link" href="/oss/integrations/retrievers/self_query" arrow="true" cta="View guide" />
<Card title="SVM" icon="link" href="/oss/integrations/retrievers/svm" arrow="true" cta="View guide" />
<Card title="TavilySearchAPI" icon="link" href="/oss/integrations/retrievers/tavily" arrow="true" cta="View guide" />
<Card title="TF-IDF" icon="link" href="/oss/integrations/retrievers/tf_idf" arrow="true" cta="View guide" />
<Card title="NeuralDB" icon="link" href="/oss/integrations/retrievers/thirdai_neuraldb" arrow="true" cta="View guide" />
<Card title="ValyuContext" icon="link" href="/oss/integrations/retrievers/valyu" arrow="true" cta="View guide" />
<Card title="Vectorize" icon="link" href="/oss/integrations/retrievers/vectorize" arrow="true" cta="View guide" />
<Card title="Vespa" icon="link" href="/oss/integrations/retrievers/vespa" arrow="true" cta="View guide" />
<Card title="Wikipedia" icon="link" href="/oss/integrations/retrievers/wikipedia" arrow="true" cta="View guide" />
<Card title="You.com" icon="link" href="/oss/integrations/retrievers/you-retriever" arrow="true" cta="View guide" />
<Card title="Zep Cloud" icon="link" href="/oss/integrations/retrievers/zep_cloud_memorystore" arrow="true" cta="View guide" />
<Card title="Zep Open Source" icon="link" href="/oss/integrations/retrievers/zep_memorystore" arrow="true" cta="View guide" />
<Card title="Zilliz Cloud Pipeline" icon="link" href="/oss/integrations/retrievers/zilliz_cloud_pipeline" arrow="true" cta="View guide" />
<Card title="Zotero" icon="link" href="/oss/integrations/retrievers/zotero" arrow="true" cta="View guide" />
</Columns>

